404 Page At Checkout

Had a customer call today but I think it may be happening more often as orders seem to have dropped some.

As they progress from choosing credit card payment anf hit continue which shoudl take them to the payment processor "sagepay" they get 404.

I also asked the to try using telephone payment which also went to a 404.

I tried gathering info from customer but they werent able to give the the exact url, only that they were using safari on a mac. I have tried on a test tool but seems to work ok.

Any ideas anyone ?

More than likely an addon is failing that works off of that step r the 'summary' page. Do you know if the payment has been placed? Generally addons work post-payment, but some may try to do their thing before payment since payment may leave site and not return until summary.

Can you want it in browser inspector and see what page is generating the 404?

What do you see in the server error logs?